A texture design method to improve surface friction reduction performance

Abstract

A texture design method for improving surface friction reduction performance belongs to the fields of aluminum alloy surface treatment and surface texture design technology. It includes the following steps: S1, selecting from the texture structures processed on the aluminum alloy surface, determining the basic shape and size range of individual micro-textures within the selected surface textures; S2, modeling the individual micro-textures and optimizing their basic shape and size through numerical simulation; S3, obtaining the optimal shape and size of the individual micro-texture based on the structure simulated in step S2. This invention, through the variable density texture arrangement, can generate a significant pressure and velocity difference between the bottom of the micro-texture and the aluminum alloy surface. The bottom of the texture, accompanied by backflow, generates negative pressure, forming a gas-liquid coexistence cavitation phenomenon. An asymmetric positive pressure is formed on the aluminum alloy surface, causing the friction pair to separate from the surface, reducing its surface friction coefficient and decreasing wear.

Description

Technical Field

[0001] This invention belongs to the fields of aluminum alloy surface treatment and surface texture design technology, specifically relating to a texture design method for improving surface wear reduction performance. Background Technology

[0002] In recent years, the research on the anti-wear mechanism of aluminum alloy surfaces has attracted widespread attention from researchers. In the aerospace field, aluminum alloys are the main raw material for manufacturing aerospace equipment. During service, the transmission system of aerospace equipment often enters a lean-lubrication state due to insufficient oil supply and failure to form oil lubrication after the aluminum alloy surfaces of its components wear and damage, affecting the stability of the equipment. Surface textures can store lubricating oil and reduce the coefficient of friction, which can maintain the normal operation of the transmission system for a certain period of time. However, research on the preparation of anti-wear microtextures on aluminum alloy surfaces is currently lacking, and a reliable design method for anti-wear functional microtextures on aluminum alloy surfaces is needed to solve this problem.

[0003] In nature, geese are observed to fly south in a V-shaped formation, which reduces air resistance and conserves energy. This natural phenomenon has inspired researchers to design and fabricate V-shaped textures on material surfaces and conduct friction and wear tests to investigate whether this can reduce the surface friction coefficient. The research found that this texture can reduce the friction coefficient of material surfaces under oil lubrication conditions. However, to further improve the surface's anti-friction performance, the design of the V-shaped texture's size, density, and arrangement is highly subjective, and existing V-shaped surface texture technologies do not provide specific design standards. Summary of the Invention

[0004] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a texture design method to improve surface friction reduction performance; textured hydrodynamic lubrication helps to improve the wear of aluminum alloy components in the transmission system of aerospace equipment and improve the working stability of aerospace equipment.

[0005] This invention provides the following technical solution: a texture design method for improving surface friction reduction performance, comprising the following steps:

[0006] S1. On the aluminum alloy surface with a textured structure, select a surface texture structure, and determine the basic shape and size range of a single microtexture based on the selected surface texture shape.

[0007] S2. Model a single microtexture and use numerical simulation to optimize the basic shape and size of the microtexture;

[0008] S3. Based on the results of the numerical simulation in step S2, a variable density arrangement design is carried out for the surface texture, the microtexture spacing size under this arrangement is determined, and a multi-column texture arrangement model with different microtexture depths is established. Then, the microtexture depth parameters are optimized through numerical simulation to obtain the optimal shape and size of a single microtexture, and the microtexture design for the aluminum alloy surface wear reduction function is completed.

[0009] Furthermore, step S2 includes the following specific steps:

[0010] S2.1 Single microtexture modeling: Based on the basic shape and size range of the basic shape of the single microtexture determined in step S1, a size model of the single microtexture is established using 3D modeling software;

[0011] S2.2 Numerical Simulation: The established single microtexture model is meshed and then subjected to numerical simulation.

[0012] Furthermore, the specific process of step S3 is as follows:

[0013] S3.1 Determine the shape and size parameters of a single microtexture: Analyze the variation law of surface velocity and pressure distribution of the microtexture based on the numerical simulation results in step S2, evaluate the wear reduction and wear resistance performance of a single microtexture unit, and analyze the influence trend of the edge length and depth of the texture on the friction coefficient in order to determine the shape and size parameters of a single microtexture.

[0014] S3.2 Design of textured variable density arrangement and microtexture depth range: Textured arrangement is carried out on the aluminum alloy surface, and a textured distribution area is defined. This distribution area is the preset wear area. Different textured distribution densities are set in each preset wear area, and the depth range of microtexture in each preset wear area is designed according to the basic theory of drag reduction microtexture design.

[0015] S3.3 Calculate the number of textures in each preset wear area;

[0016] S3.4. Based on the number of textures in each preset wear area obtained in step S3.3, calculate the texture spacing in the corresponding preset wear area.

[0017] S3.5 Multi-column micro-texture modeling and numerical simulation: Based on the texture spacing and shape and size of a single micro-texture in each preset wear area, multi-column micro-texture unit models of different depths are established using 3D modeling software, and numerical simulation is performed on the established multi-column micro-texture unit models.

[0018] S3.6 Determining the texture depth and verifying the model: Based on the numerical simulation results, analyze the variation law of velocity distribution and pressure distribution on the surface of multiple microtextures, evaluate the wear reduction and wear resistance performance of each microtexture according to the formulas of friction coefficient and pressure coefficient, analyze the influence trend of each characteristic parameter on the friction coefficient, and determine the texture depth; further, based on the analysis results, summarize the optimal characteristic parameters to analyze the wear reduction effect, and verify that the selected parameters have the optimal wear reduction effect.

[0019] By employing the above-described technology, the beneficial effects of the present invention compared to the prior art are as follows:

[0020] 1) The present invention can generate a significant pressure difference and flow rate difference between the bottom of the microtexture and the aluminum alloy surface by means of a variable density texture arrangement. The bottom of the texture generates negative pressure with backflow, forming a gas-liquid coexistence cavitation phenomenon. The aluminum alloy surface forms an asymmetric positive pressure, which separates the friction pair from the surface, reduces its surface friction coefficient and reduces wear.

[0021] 2) The surface texture unit involved in this invention can not only store a certain amount of wear debris and lubricating oil during the wear process, thereby reducing the wear of the aluminum alloy surface; but also further ensure the stability of the friction interface and service life of aluminum alloy products. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the V-shaped microtexture design parameters in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the basic dimensional parameters of the V-shaped microtexture in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the variable density arrangement in an embodiment of the present invention;

[0025] Figure 4 for Figure 3 A magnified view of a portion of the Q1 sector.

[0026] Figure 5 This is a cross-sectional pressure distribution cloud map obtained from numerical simulation of multiple microtextures in an embodiment of the present invention;

[0027] Figure 6 This is a cross-sectional velocity cloud map obtained from numerical simulation of multiple microtextures in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0030] Please see Figure 1-6 A texture design method for improving surface abrasion reduction performance includes the following steps:

[0031] S1. On the aluminum alloy surface with a textured structure, select a surface texture structure, and determine the basic shape and size range of a single microtexture based on the selected surface texture shape.

[0032] S2. Model a single microtexture and optimize its basic shape and size using numerical simulation. The specific process is as follows:

[0033] S2.1 Single microtexture modeling: Based on the basic shape and size range of the basic shape of the single microtexture determined in step S1, a size model of the single microtexture is established using 3D modeling software;

[0034] S2.2 Numerical Simulation: The established single microtexture model is meshed and then subjected to numerical simulation.

[0035] S3. Based on the numerical simulation results in step S2, a variable density arrangement design for the surface texture is implemented. The microtexture spacing size under this arrangement is determined, and a multi-column texture arrangement model with different microtexture depths is established. Then, the microtexture depth parameters are optimized through numerical simulation to obtain the optimal shape and size of a single microtexture, thus completing the microtexture design for the aluminum alloy surface friction reduction function. The specific process is as follows:

[0036] S3.1 Determine the shape and size parameters of a single microtexture: Analyze the variation law of surface velocity and pressure distribution of the microtexture based on the numerical simulation results in step S2; evaluate the wear reduction and wear resistance performance of a single microtexture unit: pit-type microtextures mainly reduce the friction wear of the friction pair by improving the load-bearing capacity of the lubrication mold, and the load-bearing capacity of the lubrication film is closely related to the pressure distribution of the lubrication film. Therefore, the pressure distribution of the lubrication film can be used to analyze the influence of texture geometry parameters on the friction performance of the friction pair; analyze the influence trend of the edge length and depth of the texture on the friction coefficient to determine the shape and size parameters of a single microtexture.

[0037] S3.2 Design of textured variable density arrangement and microtexture depth range: Textured arrangement is carried out on the aluminum alloy surface, and a textured distribution area is defined. This distribution area is the preset wear area. Different textured distribution densities are set in each preset wear area. The depth range of microtexture in each preset wear area is designed according to the distance between the upper and lower contact surfaces of the friction pair in hydrodynamic lubrication.

[0038] S3.3 Calculate the number of textures in each preset wear area;

[0039] S3.4. Based on the number of textures in each preset wear area obtained in step S3.3, calculate the texture spacing in the corresponding preset wear area.

[0040] S3.5 Multi-column micro-texture modeling and numerical simulation: Based on the texture spacing and shape and size of a single texture in each preset wear area, a multi-column texture unit model is established using 3D modeling software, and numerical simulation is performed on the multi-column texture unit model.

[0041] S3.6 Determining the texture depth and verifying the model: Based on the numerical simulation results, analyze the variation law of velocity distribution and pressure distribution on the surface of multiple microtextures, evaluate the wear reduction and wear resistance performance of each microtexture according to the formulas of friction coefficient and pressure coefficient, analyze the influence trend of each characteristic parameter on the friction coefficient, and determine the texture depth; further, based on the analysis results, summarize the optimal characteristic parameters to analyze the wear reduction effect, and verify that the selected parameters have the optimal wear reduction effect.

[0042] Example:

[0043] A texture design method for improving surface friction reduction performance is proposed. First, the basic shape and size range of the microtexture are determined. Then, individual microtextures are modeled and their basic shape and size are optimized through numerical simulation. Next, the spacing between microtextures is determined based on the density of the designed variable-density arrangement, and a multi-column texture arrangement model with different microtexture depths is established. Finally, the microtexture depth parameters are optimized through numerical simulation to complete the microtexture design for friction reduction on aluminum alloy surfaces.

[0044] The specific process is as follows:

[0045] 1. Design the basic shape and size range of microtextures

[0046] like Figure 1 As shown, the basic shape of the microtexture is V-shaped, composed of two equilateral triangles. The design shape parameters include the outer side length O, inner side length I, and width T of a single V-shaped texture, as shown below. Figure 1 As shown. Based on the basic theory of drag-reducing microtexture design, the range of the longest side O parameter of the microtexture is set to 300-1000μm.

[0047] 2. Single micro-weave construction model

[0048] Based on the range of shape parameters of the designed texture, different basic shape dimensions of a single texture are set, and multiple size models of a single V-shaped micro-texture are created using SolidWorks software.

[0049] 3. Numerical simulation

[0050] The established model was imported into Ansysmesh for mesh generation, and numerical simulation was performed using Fluent software.

[0051] The fluid continuity equation is calculated using the Navier-Stokes equations, and the basic formula is as follows:

[0052]

[0053]

[0054]

[0055] In the formula, ρ is the fluid density.

[0056] u,υ,w——The components of the fluid velocity along the x, y, z directions at time t;

[0057] p – pressure;

[0058] f represents the external force acting on a unit volume of fluid. If only gravity is considered, then f = μg; the constant μ is the dynamic viscosity.

[0059] To solve the continuity equation and close the equation, a fluid control model needs to be established. Considering the flow of fluid through the pit texture unit, the velocity between adjacent fluid layers is not only gradient-distributed in the velocity direction, but also has a corresponding gradient distribution inside the pit perpendicular to the velocity direction. The fluid flow velocity on the texture surface under study is relatively fast, so the standard K-ε model in the turbulence model is selected as the fluid control model.

[0060] The fluid's ability to carry loads on the upper surface of the friction pair is used as the pressure coefficient C for the smooth upper surface. p To represent:

[0061]

[0062] In the formula, p i —Unit area pressure;

[0063] p0—Standard atmospheric pressure;

[0064] q0 — Reference dynamic pressure Where ρ0 and v0 are the reference density and reference velocity, respectively, taken as 1.225 kg / m³ and 1 m / s.

[0065] The coefficient of friction C of the fluid along the direction of motion f Represented as:

[0066]

[0067] In the formula: A f —Texture area

[0068] η—Dynamic viscosity,

[0069] ρ — density of lubricating oil

[0070] i — the number in the summation formula, which can be 1, 2, 3, 4...n, and has the same meaning as the i in the summation symbol at the beginning of the formula.

[0071] v — fluid velocity

[0072] A – The total area of ​​the calculation region.

[0073] 4. Determine the shape and size parameters of individual textures

[0074] Based on the numerical simulation results, the variation laws of velocity and pressure distribution on the microtexture surface are analyzed. Using the pressure coefficient and friction coefficient formulas from the numerical simulation, the wear-reducing and wear-resistant performance of a single microtexture unit is evaluated. The influence trend of each characteristic parameter on the friction coefficient is analyzed, and the shape and size parameters of a single texture are determined as follows: outer side length O = 700 μm, inner side length I = 400 μm, and width T = 150 μm. Figure 2 As shown.

[0075] 5. Design of variable density texture arrangement and range of microtexture depth

[0076] The texture is distributed on the aluminum alloy surface in a clockwise direction with three varying densities. This distribution area is the pre-defined wear zone, arranged in a ring shape. The inner diameter of the ring is D1 = 10 mm, and the outer diameter is D2 = 16 mm. This ring is divided into three fan-shaped areas with a central angle of 120°. The designed texture distribution densities for the three areas are 10%, 15%, and 20%, respectively. Figure 3 Based on the fundamental theory of drag-reducing microtexture design, the depth range of the V-shaped microtexture is designed to be 30-50 μm.

[0077] 6. Calculate the number of texture regions

[0078] Calculate using the formula for sector area Figure 3 The area of ​​sector Q1 is 41 mm². 2 Based on the designed texture distribution density in each region, the total area of ​​the texture unit distribution in the Q1 sector is calculated to be A = 4.1 mm. 2Based on the determined individual texture shape and size parameters, the area of ​​the texture unit is calculated to be U = 0.143 mm². 2 According to the formula The texture number of the Q1 sector region is calculated to be 27, where A is the total area of ​​the annular region and U is the area of ​​the texture unit.

[0079] 7. Determine the texture spacing

[0080] The textures are arranged at equal intervals in each region. The spacing between textures in each region is calculated based on the number of textures in that region. The spacing is expressed as follows: Figure 4 As shown, the formula for calculating the adjacent radial spacing of the texture along the radial direction is:

[0081]

[0082] In the formula, R1 is the radius of the circle within the wear area;

[0083] R2—Relative of the outer circle of the wear zone;

[0084] O – Length of the outer edge of the texture unit;

[0085] K — Number of gaps along the radial direction

[0086] The formula for the adjacent axial spacing of the texture in region Q1, perpendicular to and radially, is as follows:

[0087]

[0088] In the formula, L1 is the arc length within the Q1 region;

[0089] N1—Number of inner circle texture units;

[0090] Similarly, calculate and The radial spacing d of the texture is obtained a =0.5mm, axial spacing of region Q1 Axial spacing in region Q2 Axial spacing in Q3 region

[0091] 8. Multi-column micro-weave construction modeling and numerical simulation

[0092] Based on the required texture spacing and individual texture shape dimensions, a texture model is created using SolidWorks software. Figure 3 The multi-column texture unit model is shown in the arrangement. Similar to the numerical simulation process for a single texture model, numerical simulation is performed on the multi-column micro-texture model.

[0093] 9. Determine texture depth and verify the model

[0094] The variation patterns of velocity and pressure distribution on the surface of a multi-column microtexture were analyzed based on numerical simulation results. The pressure and velocity contour maps obtained for a single microtexture unit are shown below. Figure 4 As shown. The wear-reducing and wear-resistant performance of each microtexture was evaluated based on the formulas for the friction coefficient and pressure coefficient. The influence trend of each characteristic parameter on the friction coefficient was analyzed, and the texture depth was determined to be 30 μm. Further, based on the analysis results, the wear-reducing effect of each optimal characteristic parameter was analyzed, verifying that the selected parameters have the optimal wear-reducing effect.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A texture design method for improving surface friction reduction performance, characterized in that: Includes the following steps: S1. On the textured aluminum alloy surface, select a surface texture structure, and determine the basic shape and size range of a single microtexture based on the selected surface texture shape; the basic shape of a single microtexture is V-shaped. S2. Model individual microtextures and optimize their basic shape and size through numerical simulation. S3. Based on the numerical simulation results in step S2, a variable density arrangement design for the surface texture is implemented to determine the microtexture spacing size under this arrangement, and a multi-column texture arrangement model with different microtexture depths is established. Then, the microtexture depth parameters are optimized through numerical simulation to obtain the optimal shape and size of a single microtexture, thus completing the microtexture design for the aluminum alloy surface friction reduction function. The specific process of step S3 is as follows: S3.1 Determine the shape and size parameters of a single microtexture: Analyze the variation law of surface velocity and pressure distribution of the microtexture based on the numerical simulation results in step S2, evaluate the wear reduction and wear resistance performance of a single microtexture unit, and analyze the influence trend of the edge length and depth of the texture on the friction coefficient in order to determine the shape and size parameters of a single microtexture. S3.2 Design of textured variable density arrangement and microtexture depth range: Textured arrangement is carried out on the aluminum alloy surface, and a textured distribution area is defined. This distribution area is the preset wear area. Different textured distribution densities are set in each preset wear area, and the depth range of microtexture in each preset wear area is designed according to the basic theory of drag reduction microtexture design. S3.3 Calculate the number of textures in each preset wear area; S3.

4. Based on the number of textures in each preset wear area obtained in step S3.3, calculate the texture spacing in the corresponding preset wear area. S3.5 Multi-column micro-texture modeling and numerical simulation: Based on the texture spacing and shape and size of a single micro-texture in each preset wear area, multi-column micro-texture unit models of different depths are established using 3D modeling software, and numerical simulation is performed on the established multi-column micro-texture unit models. S3.6 Determining the texture depth and verifying the model: Based on the numerical simulation results, analyze the variation law of velocity distribution and pressure distribution on the surface of multiple microtextures, evaluate the wear reduction and wear resistance performance of each microtexture according to the formulas of friction coefficient and pressure coefficient, analyze the influence trend of each characteristic parameter on the friction coefficient, and determine the texture depth; further, based on the analysis results, summarize the optimal characteristic parameters to analyze the wear reduction effect, and verify that the selected parameters have the optimal wear reduction effect.

2. The texture design method for improving surface friction reduction performance according to claim 1, characterized in that... Step S2 includes the following specific steps: S2.1 Single microtexture modeling: Based on the basic shape and size range of the basic shape of the single microtexture determined in step S1, a size model of the single microtexture is established using 3D modeling software; S2.2 Numerical Simulation: The established single microtexture model is meshed and then subjected to numerical simulation.

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